1. Field of the Invention
The present invention relates to a method of continuously manufacturing amorphous metal strip or crystalline metal strip by quench-solidification on the surface of a moving chill body of molten metal.
2. Description of the Prior Art
Various means have been disclosed relating to methods of continuously manufacturing strip from molten metal (continuous melt quenching method). In each case the molten alloy is ejected under a specific pressure from a nozzle having an orifice of a specific shape, and strikes a moving chill body that faces the nozzle orifice to be thereby solidified into continuous strip.
The important manufacturing factors at this time are the shape of the nozzle orifice, the relative positional arrangement of the nozzle and the chill body, the pressure at which the molten alloy is ejected from the nozzle, and advancing the chill surface at a predetermined speed. With respect to these manufacturing factors, in general, conditions tend to become narrower and more stringent as the width of the strip increases.
Japanese Patent Laid Open No. 53 (1978)-53525, "Method and apparatus for continuous casting of metal a strip", is a representative example of means that have been disclosed for manufacturing wide strip, and in outline comprised a slotted nozzle positioned generally perpendicular to the direction of movement of a chill surface and located in close proximity to the chill surface to provided a gap of from about 0.03 to about 1 mm between the nozzle and the chill surface, molten alloy was ejected from the nozzle onto the chill surface at a velocity of 100 to 2,000 meters per minute for forming continuous strip by means of thermal-contact rapid-cooling solidification.
In the above-mentioned conventional method, in principle there is no limitation on the width of the strip. That is, if the length of the rectangular orifice (the length of the orifice measured in a direction that is at right-angles to the direction of movement of the chill surface) was increased, the width of the strip could be increased.
However, in practice, as the length of the rectangular orifice was increased it became difficult to maintain the parallelism of the orifice during the casting. Specifically, as shown in FIGS. 3a and 3b, convex or concave deformation of the nozzle portion caused by thermal expansion, deformation resulting from non-uniformity of the temperature and the like made it difficult to maintain the parallelism of the orifice. When the parallelism of the rectangular nozzle is thus lost, the thickness of the formed strip, especially in the direction of the width, becomes non-uniform. Accordingly, conventionally, the wider the strip became the more difficult it has been to produce strip having uniform thickness across its width. Also, strip that is of non-uniform thickness is undesirable because when such strip is laminated or coiled, for example, the space factor deteriorates. At present it is possible to keep thickness deviation in 25-mm-wide strip down to 5 to 10 per cent, but in the case of strip 150 mm in width it difficult to keep the deviation to 10 per cent or less. Thus, with conventional methods the width of the strip was subject to a technical limitation. As far as the present inventors know, at present the width of the widest rapid-cooled strip is around 300 mm. However, strip of this width is being produced only on an experimental basis, and it is difficult to consider that production stability is such as to permit commercial mass-production.